A conventional rotary switch primarily includes a substrate, a magnetic field detection element (IC) disposed on the substrate, a rotatable dial, and an annular magnet that can rotate integrally with the dial. When the dial is rotated, the annular magnet is rotated integrally therewith, and the magnetic field detection element senses the change in magnetic flux resulting from the rotation of the annular magnet. The magnetic field detection element thus detects the direction and amount of the rotation. The details of the technology are described in the patent literature 1.
Patent literature 1: Japanese Patent Application Laid Open No. 2006-73311